The invention relates to a method, a circuit arrangement and a system for exchanging data and for supplying power to at least one current sink connected via at least one data line pair to a fire alarm control unit.
Hazard alarm systems, such as alarm systems for fire, gas, temperature, etc., generally comprise detectors, which are connected to a control unit. Such hazard alarm systems are used in public buildings, office buildings, hotels, industrial premises, airports, rail stations, workshops, etc. If an alarm is triggered at one of the detectors, the control unit is notified. The functions of the control unit can be parameterized freely and support an alarm organization system tailored to the object to be monitored. Such control units generally have an integrated operating element with a graphic display unit and interfaces with communication networks. With these control units or fire alarm control units, fire alarms, display elements, etc. are connected via a data line pair, what is known as the alarm bus, to the fire alarm control unit. Spur and loop lines are used for this purpose. The power supply to current sinks, such as graphic operating elements on the individual floors of a building, surveillance cameras, graphic display units, control relays for example for opening and closing doors, windows, etc., having a power consumption greater than 20 mA, is provided via separate power lines. For data transmission purposes the current sinks must also be connected via data lines to the fire alarm control unit.